Time Slayer
by SeaSpectre160
Summary: With all the demons running amok throughout time, the Legends recruit the world's foremost expert in killing them: the Slayer. [Written for Challenge 8685 'Time slayer' on Twisting the Hellmouth]


**This was written for Challenge 8685: 'Time slayer' on Twisting the Hellmouth. Well, actually it was the 'Spring Cleaning Challenge 2018', which was to find an unanswered challenge and respond to it. Since I'm in the middle of writing a Buffy/Legends crossover of my own, I was delighted to find this one. It took me a while, but I've finished it with a few days to spare.**

 **Now, while this challenge mentioned the upcoming crossover, I won't be going into detail on that because it's still several months away, and all I know at this point is that it involves Gotham and Batwoman. And I don't know if Wally's going to stay on for Season 4 or not (promotional material suggests that he won't), but for the sake of this fic, let's assume he's sticking around for at least a little while.**

 **Just so you know, I have not read the comics, so anything that happened in them is not necessarily part of this continuity. I do check the Buffyverse Wiki for reference, so some details may have been from the comics, but I pick and choose what I use.**

 **DISCLAIMER: I do not own 'Buffy the Vampire Slayer' or any of its characters. It belongs to Mutant Enemy Productions. I also do not own 'DC's Legends of Tomorrow' or any of its characters. It belongs to Berlanti Productions, DC Entertainment, and Warner Bros. Television.**

 **WORD COUNT: 4250**

* * *

"Are you sure you have everything?"

"Yes, Giles, I'm sure." Buffy rolled her eyes as she shouldered her overstuffed duffel bag. "I've got a week's worth of clothes for each season and every type of weather, I have the entire Slayer Library on my E-Reader, I've got about a dozen swords and knives, two crossbows, and I also have enough wooden stakes and crossbow bolts to recreate Noah's Ark. For God's sake, I have _Olaf's hammer_! On top of that, Willow's also packing up a portable magic kit for me, but she'll be bringing that to the airport with her, so I don't need to worry about it. Which means _you_ don't need to worry about it. Seriously, you're acting like my Mom did on my first day of school, minus the tears."

Giles looked somewhat embarrassed. "I- I'm sorry, Buffy, it's just that, well, after all I've learned with the Watcher's Council, and everything I've seen helping you, I thought that I'd seen everything. But time-travel, well…"

Buffy smiled wryly. "Yeah, that one's actually a new one. But you _heard_ what Robin said. They need a Slayer, and you know it."

* * *

"Okay, what's a Slayer, and why do we need one?"

Sara immediately handed the responsibility of explaining over to Constantine. This _was_ his idea, after all.

John shrugged at Nate's question, chewed on his unlit cigarette out of habit, and flicked his lighter. He knew better than to actually light up on the ship – Gideon could get _very_ creative with her punishments, as he'd found out the hard way. "Because two pros are better than one, mate. The demon-fightin' business has two sides, really: one side's all about castin' spells and performin' rituals, while the other's more 'slice-and-dice'. And no one's better at the 'slice-and-dice' than a well-trained Vampire Slayer."

 _That_ phrase immediately caught the attention of Mick, the most vampire-obsessed member of the team. "We're recruiting a guy who fights vampires?"

John shook his head. "Not a guy," he corrected, "See, way back in the cavemen days, demons were hunting humans left, right, and centre. Then some mystical shamans came up with a plan to put a stop to it. They took a young girl and performed some very powerful magicks, infusing her with the essence of a demon. The girl became stronger and faster than any normal human, with heightened reflexes and battle instincts, to boot. She became humanity's best defense against the forces of darkness. 'Course, she was still badly outnumbered, and eventually she got killed. But her powers somehow transferred to another girl, and she took up the mantle. No one's completely sure _how_ it works, but it does. Every time the current Slayer dies, a new one rises up. 'Til the late nineteen-nineties, anyway. That's when things started changin'. The Slayer that time died – think she drowned. Guess but she was lucky – had a friend who got to her in time and did CPR, brought her back to life."

"How does that change anything?" Zari asked, "Did she lose her powers?"

"Nope. And neither did her successor, neither. For the first time in recorded history, there were two Slayers at a time. Was the talk of the magic and demon communities for about six years, before the first of the two did somethin' that blew _that_ outta the water." He sat up and leaned forward. "She got her hands on an ancient weapon that was tied into the magic of the Slayer line. See, while there was only ever one Slayer at a time, there was always several hundred girls who had the potential to become the next one. But this girl had a very powerful witch for a best mate, and _that_ girl did something impossible when she got access to that magic. She turned every one of those Potentials into a fully-fledged Slayer."

Sara nodded. "There's over a thousand young women, all over the world, with the ability to kill lots of demons. The League knows about the Slayers, and their organisation. Apparently, the shamans who created the first Slayer arranged for her and her successors to always be found and trained by their own successors. They became known as the Watchers, and they had a _lot_ of influence, even if most of the world doesn't know they ever existed."

"They were also a bunch of cold-hearted buggers," John added, "Most of 'em, anyway. Saw themselves as the true heroes, while the Slayers were just the weapons they wielded against evil. The average age for a new Slayer was _seventeen_ , to put that into perspective, and they rarely made it to twenty. Luckily, the Slayer who died and came back had a personal Watcher who loves her like his own child. And the whole reason they activated every possible Slayer in the world was in response to a _very_ nasty evil that also wiped out most of the Watchers, so once they took care of that, there was a power vacuum that allowed the Slayers to be calling the shots, for once, along with the Watchers who actually gave a rat's arse about them."

"And we're recruiting one of them, to help us fight the demons?" Ray asked, just for confirmation.

"Spot on, mate. With nearly two thousand of the runnin' around, my contact in their group says they can easily spare one adventurous volunteer. I've no idea who they picked, though. Might not even be one of the girls I've met."

"Which is why John and I are taking the Jump Ship to Scotland right now," Sara finished, "We're picking up our newest recruit, and when we get back, I expect the _Waverider_ to be in one piece, or there'll be hell to pay." She stared each member of her dysfunctional team down. " _Understood?_ "

Ray and Wally nodded enthusiastically, Nate looked mildly offended, Zari shrugged and looked doubtful, and Mick just shrugged and grunted. Not exactly reassuring, but really, what else could Sara expect from this motley crew?

* * *

SCOTLAND  
2018

"I don't see a plane," Buffy commented, scanning the empty runway and then the sky, "Are they late?"

Giles shrugged, putting the car in park and getting out. He looked around the Council's private airstrip, but, like Buffy, saw no aircraft. Only Willow, who was getting out of her car in the parking spot next to theirs.

"I think they're running late," Willow guessed, wrapping Buffy in a tight hug as a greeting.

"I would expect a group of time-travellers to be more prompt," Giles criticised.

Buffy was about to say something in response, but stopped and cocked her head. "I think I hear something," she said, "But it's not like any engine I've ever heard before."

All three looked up into the sky, and all three were shocked when a vaguely jet-shaped, flying vehicle appeared overhead out of nowhere and settled down on the tarmac.

"I think that's them," Willow said in a small voice.

Buffy frowned when she realised how small it was, relatively speaking. "I thought Robin said I'd be _living_ on the time ship," she commented, "And with other people. Is there going to be enough room?"

The back end of the ship opened up, and two people walked down the ramp. Both were blonde, but that was where the similarities ended. For starters, one was a man and the other a woman. The man, about the same age as Buffy, wore a tie and dress shirt that looked like he'd slept in them under a long, brown trenchcoat, and practically swaggered up to them. And he was a smoker – Buffy could smell it from here, even if he didn't have one lit up. The woman appeared closer to Dawn's age, and she had on simple jeans, a fitted T-shirt and a jacket, and she moved like a warrior – maybe not like a Slayer, but as close as possible for a non-Slayer human.

"Hi," the woman greeted them pleasantly, "Who here wants to add 'time-traveler' to their resumé?"

"Ooh, me!" Willow squeaked, then blushed. "Except I kinda can't."

Buffy smiled and hugged her friend. "Don't worry, Will, I'll take lots of pictures." She then turned to the other two. "I'm Buffy, and this is Willow and Giles. You must be John Constantine and…" She trailed off, realising that she didn't know the woman's name yet.

"Sara Lance," she supplied, reaching out and shaking Buffy's hand, "Captain of the _Waverider_. And this is John Constantine, our resident warlock."

Said warlock was staring at Buffy with his jaw dropped. "Bloody Hell," he muttered, "Wood could've told me that we'd be workin' with the original Slayer."

Sara looked back and forth between him and Buffy. "What? The original? Not the one from the caveman days?"

Buffy chuckled and shook her head. "I guess you got the whole 'The World Is Older Than You Know' speech, huh? No, I'm not the First Slayer, but I _am_ the one who's been a Slayer the longest."

"She's the one who died and came back," John added.

Sara nodded in understanding. "Oh. Well, with all the demons we'll be facing, I'll _happily_ take the most experienced Slayer around. Welcome aboard."

Buffy grinned back, although she was still skeptical about the size of their time machine. "Thanks. Uh, not to sound like an unimpressed bitch, but I didn't expect your time machine to be that… small."

"It could be larger on the inside," Giles murmured, causing the others to look at him, "Yes, that _was_ a pop culture reference you heard. Spending enough time with Andrew does result in one picking a few things up … regardless of whether or not one wishes to do so."

"Andrew's going to be _so_ jealous of you, Buffy," Willow commented.

Sara laughed. "Technically, this thing _can_ travel through time, but this is just the Jump Ship. Our _actual_ time ship is parked in the time stream itself."

"And we should be getting' back," John muttered, "I know it's time travel, but we should probably get this done as quickly as possible."

Sara rolled her eyes at John's impatience, but agreed. "He's sort of right. Despite having a time machine, we usually find ourselves racing against the clock, anyway."

Buffy hugged Giles and Willow goodbye (Willow hugged her two extra times because Dawn and Xander both made her promise to 'Give her an extra hug for me'), then carried her deceptively small suitcase and duffel bag onto the Jump Ship.

* * *

When Trenchcoat said they were recruiting a Vampire Slayer, Mick had pictured a strong, tall, Amazon-type woman in his head. Not this tiny little blonde thing. She was even shorter than Blondie! But just thinking of Blondie reminded him that size was deceiving when it came to how dangerous someone could be. Blondie was the smallest person on the crew and easily the deadliest.

They put her in Amaya's old room. Mick wasn't too pleased with it, and neither was Pretty, but since Trenchcoat had taken Jax's room, the only other option was Leonard's quarters. And there was _no way_ Mick was letting _that_ happen. He'd put his foot down when the speedster kid moved in and had the choice between Leonard's room and Martin's (why he didn't just take Jax's room instead of one of their dead teammates' rooms was a question that never got answered).

They knew things would be interesting with Summers on board when Haircut tried to carry her tiny suitcase to her room and nearly threw out his back just trying to lift it.

"Oh, sorry," she apologised, "I've got a troll hammer in there. You kind of need super-strength to lift that thing."

"I've got it, then," Pretty volunteered, then he Steeled up and carried the case out of the room.

With all the praise Trenchcoat'd heaped on the Slayers, it was natural that Summers would be swarmed with people asking a ton of questions about her exploits. And it was only natural that Mick would be right in the thick of it.

He'd read and watched almost everything he could that had to do with vampires. Really, Mick still couldn't believe it took him _so long_ to finally read the original 'Dracula'. 'Twilight' made no sense. Bela Lugosi was _the_ Dracula. And he was _still_ waiting for the tenth 'Night World' book to finally come out. So yeah, here was someone who actually met real vampires, and killed a bunch of them. You bet your ass Mick had questions.

"How many vampires have you killed?"

"I lost count over a decade ago."

"Do the holy water and crosses and garlic really work?"

"Yes, yes, and only if they _really_ hated garlic in life."

"You ever screw one?"

Haircut spit his drink out at that one. "MICK!" he squawked, " _So_ not appropriate!"

But Summers looked sheepish. "Well…"

New Girl stared at her, which wasn't the best-looking sight, since she still had her half-chewed lunch in her mouth. "You slept with-" She swallowed before starting over. "You slept with a _vampire_?!"

"I dated one in high school, but we were only intimate once. And he was different from the others! He had a soul!"

Trenchcoat scoffed. "Y'mean to say those rumours were true, love? A vampire with a soul?"

"Yeah. He killed a young Romani girl, putting him in the crosshairs of her clan."

"Ahh… I see what you're gettin' at. I've seen what Gypsy magic can do. They put a curse on him, didn't they?"

"They did. They managed to restore his soul. He'd been a vampire for a long time, committed a lot of atrocities… They gave him the ability to feel guilty for what he'd done. Hundreds of years' worth. So he did his best to atone. We fought the darkness, side-by-side. Until it got complicated- well, _more_ complicated." She shifted uncomfortably. "Can we please talk about something else?"

Haircut, of course, was quick to change the subject for her. "So, uh, are there any questions _you_ have for _us_?"

Summers smirked. "Not as much from me, personally, but I have a bunch of friends who are total geeks, and they each gave me a _list_. But for now, I'd settle for a tour."

* * *

Buffy wasn't as much of a sci-fi geek as Willow, Andrew, Xander, and a few others, but she was definitely in awe of this ginormous time machine. The galley was awesome, able to create any food she wanted – which was a good thing, considering how much a Slayer needed to eat. Her quarters were a decent size, not the tiny closet she was expecting.

And speaking of closets…

She was in _love_ with the fabricator room. A gigantic walk-in closet that could create _any_ item of clothing she wanted. Any pair of _shoes_ she wanted. It was a Cali girl's _dream_. She couldn't _wait_ to use it.

What she was _not_ in love with was the fact that there was only one bathroom. It was an arrangement she was familiar with, having had to share a bathroom with Dawn and her mom for years, and sharing with the younger Slayers in various Council headquarters and lodgings. If she wasn't the new girl on the crew, and not wanting to make a good impression, she would have gladly used her Slayer strength to muscle her way in past whoever got there at the same time as her – experience told her that there would _always_ be someone else arriving at the same time.

As for her new teammates, her first impressions were pretty good, all things considered. They were quite a collection of oddballs: the rough-spoken warlock, the super-powered historian, the friendly inventor, the young speedster, the hacker from the future, and the pyro who was _way_ too interested in her past with Angel (and probably Spike, but luckily she'd managed to avoid mentioning him, so far). And they were all led by a trained assassin who, according to what little Buffy had heard from the others, fit Buffy's initial assessment: that she was as close to a Slayer as normal-humanly possible.

Her first morning on the ship was… interesting. She woke up, and had to wait for Mick, Zari, and Wally to finish before she could get into the bathroom (although Wally took less than half a minute). Then it was breakfast in the galley – fresh fruit and waffles, just like how Mom made them. After that, Capt. Lance ("Call me Sara") insisted on spending time in the training room to assess her capabilities.

Buffy was able to lift all but the heaviest of the weights with ease. She could still lift the heaviest weights, but it took some effort. Sara said they were made of something called 'Dwarf Star alloy', and it was one of the densest materials that they had access to. Normally only Nate used those weights, but Buffy was glad that they had _something_ that gave her a bit of a challenge.

The salmon ladder was interesting. Buffy picked up on its use pretty quickly, and soon resolved to ask Giles if she could get some installed in various Slayer training facilities.

Then Sara asked her to spar. Buffy was more than a bit hesitant. Sparring with Riley had proven that even a well-trained fighter could get hurt in a friendly match against a Slayer. But Sara was insistent. "I need to know what you're capable of before I send you into the field with my team."

Buffy held back, of course. She didn't want to make a bad impression with the Legends by putting the team's Captain in the infirmary on her second day. She stayed mostly on the defensive, which wasn't all that hard to do, considering how well-aimed Sara's strikes were, and how quickly they were coming.

Sara caught on to her quickly, though. "Come on!" she urged, throwing a vicious punch that Buffy barely dodged, "Show me what you've got!"

Buffy sighed. "Okay, you were warned." She ducked under the swing and chose her angle before ducking back and kicking Sara in the gut.

The assassin-turned-Time-Captain flew through the air and landed _hard_ on a pile of exercise mats in the corner.

"Sorry!" Buffy apologised, "Are you okay?"

"Ugh…" Sara groaned as she sat up, "I'll live."

"I kind of did still hold back," Buffy admitted, "But only so that you would land on the mats, and not the wall behind them."

"Okay, okay, I've got it. Sparring with non-powered people is an issue. Gideon, get Nate down here, now."

Buffy had an easier time letting loose as she smacked the man with metal skin all around the training room. His strength was certainly on par with that of Slayer, actually even more so. But he'd only been training on and off for a couple years, according to Sara, and most of it wasn't with her. Buffy was easily able to outmanoeuvre him and put him on the mat.

That was the morning. The afternoon was far more eventful, but it was the kind of eventful she was used to.

* * *

SHARPSVILLE  
1723

"Holy shit!"

That was literally the only thing that came to mind when Zari caught sight of the newest monster they would be facing.

"And I thought Mallus was big," Nate commented faintly.

"Oh, you've _got_ to be kidding me," Buffy groaned, "I _thought_ the name of this place sounded familiar!" Everyone looked at her, so she elaborated: "This isn't just any demon. It's an Old One, a _pure_ demon."

"Oh, bloody hell," John grumbled.

"They mostly don't exist anymore. I've fought one, and by 'fought', I mean I lured it into a school library full of high explosives and got the hell out of there before my Watcher blew the place sky-high."

"Does this mean I get to blow somethin' up?" Mick asked eagerly.

"Possibly," Sara allowed, "First, we need to evacuate the town. Wally?"

"On it." The yellow-and-red-suited speedster took off, only to come back seconds later. "I can't find anyone. At least, not anyone human."

"I guess we didn't get here soon enough," Buffy sighed, "This thing used to be human. He or she used a ritual called the 'Ascension' to become this monster, and they have _big_ appetites right after the transformation."

"Well, I sure as hell don't feel like being its next meal," John stated, "Any ideas?"

"I have one," Ray offered, "I can shrink it down to a more manageable size."

"Alright," Sara agreed, "But be careful. Don't let _any_ of those arms hit you."

As Ray took off, Zari pointed at the large crowd of lesser demons that were coming toward them. "How about those?"

Buffy only smirked, a purely predatory expression that made Zari feel slightly unnerved. "Easy. I do what I came on this ship to do."

With that one-liner, the Slayer unsheathed her sword and charged forward without hesitation.

* * *

Over the years, Buffy had come to accept that this, the hunting and the killing, was part of who she was. So she wasn't overly bothered at the rush she got when the demons descended on her, or the thrill she felt when her sword lopped the first one's head off, then sliced all the way through the second one's torso. She may not feel the same way about the kill, the hunt, the same way Faith and Dracula had both claimed she did, but they weren't entirely wrong.

Behind her, she could hear the sounds of the rest of her new team charging in. In between demons, Buffy caught glimpses of their fights. Sara was kicking ass as expected, wielding a sword of her own, and Nate was fully Steeled up and bashing in demon heads left and right. Mick was busy making demon flambé, while Zari was using her magic necklace to command the winds, lifting herself out of the demons' reach, sweeping them way up high in a tornado, then letting them drop to their deaths. John Constantine seemed decent enough with a sword, but he was relying more on his magic, instead, using some of the tricks Willow would employ in the field, like levitating sharp objects or summoning fire, or occasionally levitating a demon and stabbing it while it was immobilised. Wally was just a blur of yellow and lightning, leaving decapitated demons in his wake thanks to his speed and a short sword.

Ray was the only one who wasn't on the actual battlefield. He was flying around, trying to get a shot at the big demon with his shrink ray. It wasn't all that easy, since the Old One had about a dozen limbs that were trying to snatch him right out of the air.

Eventually, all the lesser demons that they could find were dead. The only one left was the Old One. Mick was the first to open fire, and Wally started running around in a circle around the demon before actually _hurling_ the lightning he generated at the demon.

Neither fire nor lightning seemed to actually _hurt_ the Old One, but they _definitely_ got its attention. Four of its giant, clawed appendages slammed down onto the ground where the pyro and the speedster had been standing (Wally yanked Mick out of the way), leaving _huge_ holes in the dirt road they were fighting on.

The distraction was enough for Ray to get a shot in with his shrink ray, only for the Old One to finally slap him out of the air. The good news, however, was that he was more Balthazar-sized than Mayor/Olvikan- sized, even if Buffy would have preferred Gachnar-sized. But she was pretty sure she could handle this.

One swipe of a sword cleaved one limb from the demon's body, then another. Sara and Wally got in on the action with their swords, until the Old One was just a writhing, growling, oozing torso.

"So, how did you say you killed one of these again?"

Buffy smirked, raised her sword, and chopped the demon's head off. "It involved lots of explosives, but decapitation also works pretty well with most demons. Still, we'd better cover all the bases."

Sara nodded at Mick. "Sounds like that's your cue, Rory."

Mick had a _huge_ grin on his face as he incinerated each and every piece of the Old One. He had an unholy light in his eyes as he watched it all burn – Sara had to physically pull him back when the blaze got too big to stand closely.

Buffy sheathed her sword and stretched. "Well, that was a fun first day."

THE END

* * *

 **I figured Sara would already know about the existence of the Slayers, because there's no _way_ the League of Assassins wouldn't know about them.**

 **For LoT fans who are unfamiliar with Buffy, The demon the Legends fight is the demon mentioned late in Buffy S3. It was one of the few known Ascensions, and took place on May 26th, 1723. The town of Sharpesville was completely destroyed, with no survivors; the only record was from the pastor's journal, found in the rubble. The Big Bad in S3 was the Mayor of Sunnydale, who completed the Ascension and became the demon Olvikan and was killed when they blew up the high school with him in it. Balthazar was the disgusting demon 'in desperate need of a Stairmaster' from 3x14 'Bad Girls', and Gachnar was the 3-inch-tall fear demon in 4x04 'Fear, Itself'. Buffy killed the latter by simply stepping on him.**

 **In 'Constantine', the man in question isn't shown to be much of a physical fighter, at least not up to the standards of other Arrowverse characters. Whenever he gets into a brawl with other people, it usually consists of him getting in a few good punches before getting his ass handed to him. Or he wins the fight simply by dodging enough to save his life or using magic. The only time he has displayed combat competence was in 'Haunted', where he took on an illusionary assassin with a sword. And in the draft script for the unproduced episode 'Final Girl', he apparently takes down a mattock-wielding killer zombie with a metal rod and a large amount of luck.**

 **I should mention here that, when writing anything involving John Constantine, I take 'Final Girl' as canon. Unless the upcoming fourth season of 'Legends' says anything that contradicts it, 'Final Girl' happened. If you haven't read it, the draft script is available on Dropbox. One possible shortcut, which is how I found it, is by looking up 'Final Girl' on the Arrowverse Wiki. The link is in the 'External Links' section.**


End file.
